This invention relates generally to fuel filters employed in connection with internal combustion engines. More particularly, the present invention relates to fuel filter systems having a replaceable cartridge for removing foreign particles and/or separating water from fuel of the fuel supply system of an internal combustion engine.
It has long been recognized that trouble-free operation of an internal combustion engine requires some form of filtering of the fuel consumed by the engine. In particular, the absence of high standards of quality control in diesel fuel supplies dictates that an effective fuel filter be incorporated into the fuel supply system for a diesel engine. It is not uncommon for diesel fuel to contain significant quantities of abrasive particles and water. The abrasive particles present the potential for permanent damage to components of the fuel injection pump. The abrasive particles can also adversely effect the performance of the pump by destroying the ability of the fuel injection pump to precisely meter and deliver fuel at high pressures. The presence of water in the diesel fuel supply can cause rusting of engine components, and during freezing conditions, can result in interruption of the fuel injection system and/or seizure of moving components.
A number of conventional fuel filter systems perform the dual functions of removing particulate matter from the diesel fuel and separating water from the fuel. Conventionally, the fuel filter systems employ a disposable filter cartridge which is replaced at pre-established intervals of filter usage. In practice the filter cartridge requirements may vary depending upon such characteristics as the type and make of the internal combustion engine, the specific applications for which the engine is employed, the climate in which the combustion engine is operated and/or regional characteristics as to the quality of the fuel supply. The filter cartridges thus commonly vary as to their dimensions, their capacity, and the qualities of their filter media.
One of the problems which is frequently encountered in connection with replacement of the filter cartridge is ensuring that the replaced cartridge is compatible with the filtering requirements for the fuel system. Because numerous types and qualities of filter cartridges may dimensionally conform to the base of a given filter system, the replacement filter cartridge frequently does not comply with the specifications for the filter system, thereby jeopardizing the integrity of the fuel filtering system. Use of an incompatible filter cartridge can have very serious effects on the operation of the internal combustion engine, and may also be unnecessarily expensive when a less costly cartridge is fully suitable. Frequently, either the owner or the maintenance personnel servicing the internal combustion engine are totally unaware of the replacement filter cartridge specifications and requirements and unknowingly jeopardize the integrity of the filtering system by using non-conforming filter cartridges. There are also instances where inferior or improper replacement filter cartridges are intentionally installed without the knowledge of the owner or operator of the vehicle.
U.S. Pat. No. 5,035,797, which is assigned to the assignee of the present invention, discloses a key system for a filter system intended to address issues of filter cartridge compatibility. Fuel filter systems commonly comprise fuel inlet and outlets disposed in a base and a disposable filter cartridge which mounts to the base. Disposable filter cartridges constructed according to this invention have slots which are designed to mate with axial projections of the base. The projections interfere with the use of an incompatible cartridge by interfering with the mounting and sealing of the cartridge to the base.
Fuel filters have typically been constructed in the form of a metal can, permanently enclosing the filter element in a single use assembly. While these assemblies have proved to be effective and reliable, they are less than ideal in terms of waste of materials and disposal cost.
Increased awareness of environmental protection and recycling of materials have led to a need for more efficient filtration systems having a minimum disposable component. In addition, environmental protection agencies seeking to reduce the volume of waste items associated with the automotive and trucking industries may no longer permit unrestricted disposal of used fuel filters into the normal waste stream, thereby necessitating specialized and consequently more expensive disposal.
Briefly stated, the invention in a preferred form is a filter cartridge assembly including a two-part housing and replaceable filter unit wherein the assembly incorporates a key system for keying the replaceable filter unit to the cartridge.
The housing is constructed of first and second cooperative sections, detachably connected to allow replacement of the used filter unit. In one embodiment, each housing section is can-shaped, having a closed first end and an open second end. The filter unit includes a continuous, fan shaped, pleated filter element, typically composed of a form of paper. Axially spaced first and second end caps provide support structure for the filter element and also provide a platform for the attachment of grommets which seal the unit to the fuel inlet/outlet conduit.
In a preferred form of the key system, at least one tab or key radially projects from either the housing first section or the filter unit first end cap. A corresponding keyway in either the other housing first section or the filter unit first end cap is dimensioned and located for receiving the corresponding key. The keyway in the housing first section takes the form of a slot having an axial portion and an offset portion generally perpendicular to the axial portion. The filter unit is guided into the housing first section axially along the cooperative keyway and key structure. The first end cap includes a radially inward projecting shoulder which, during insertion, rides over radially outward projecting ribs on the housing grommet. The ribs engage the shoulder so that the filter unit is held axially within the housing first section. In this manner the filter unit is captured and retained by the housing first section.
The cooperative keyway and key structures function as a key system to prevent the use of incompatible filter units in a particular housing. For a compatible filter unit, the angular dimension of the key will be matched by the arcuate extent of the axial portion of the keyway, and the axial dimension of the offset portion of the keyway will match the axial dimension of the key. A filter unit having a key with an incorrect angular dimension will not be accepted in the axial portion of the keyway defined by the housing first section. A filter unit having a key with an incorrect axial dimension will not properly engage the offset portion of the keyway.
In a preferred embodiment, the keys project radially from the filter unit first end cap and have radial and angular dimensions complementary with the corresponding radial depth and arcuate extent of the keyway defined by the housing first section. The filter unit key is accepted in the axial portion of the keyway, the filter unit is guided into mating position within the housing first section. The housing second section is then connected to the housing first section to form a sealed enclosure surrounding the filter unit.
The assembled housing and filter unit form a filter cartridge assembly which can be used to replace conventional, sealed filter cartridges in fuel filter systems and other applications. The key system ensures replacement filter unit compatibility for various filter cartridges having common dimensions. Unique sets of keys and keyways may be selected to form a composite compatibility matrix for each desired filter unit capacity, filter media or other characteristic, including compliance with ecological regulations or manufacturer specifications.
An object of the invention is to provide a new and improved filter cartridge assembly incorporating a system to key the replaceable filter unit to the housing.
Another object of the invention is to provide a new and improved filter cartridge assembly which allows replacement of the filter unit and provides a key system which ensures only compatible units will be used.
A further object of the invention is to provide a new and improved filter cartridge assembly key system wherein the filter unit is captured within the housing in particular axial position.
Other objects and advantages of the invention will become apparent from the drawings and the specification.